Further Studies on Proline Concentration in Grapes and Wines

Berry position in the cluster was found not to affect proline content. The relationship of sugar accumulation to proline accumulation in grape berries was demonstrated for four varieties. 9Cabernet Sauvignon9 accumulates proline at a faster rate and at lower total nitrogen levels than other varieties tested. The differences in varieties for proline concentration in wines were demonstrated by a large number of analyses of experimental and commercial wines. Fruit wines have much less proline (and total nitrogen) than grape wines. Proline concentration relates most directly to total nitrogen concentration of both grapes and wines. Saccharomyces cerevisiae will metabolize proline only under severe nitrogen starvation conditions. These conditions generally would not exist if proline were present in large amounts.